Tents

from Simon Tatham's Portable Puzzle Collection

the number of tents in each row and column matches the numbers
around the edge of the grid

it is possible to match tents to trees so that each tree is
orthogonally adjacent to its own tent (but may also be adjacent to
other tents).

Click in a square to place or remove a tent. Right-click to mark a
square as empty (not a tent). Right-click and drag along a row or
column to mark many squares at once as empty.

Warning '!' marks appear to indicate adjacent tents. Numbers round
the edge of the grid light up red to indicate they do not match the
number of tents in the row. Groups of tents light up red to indicate
that they have too few trees between them, and vice versa.